Plastic sailboat body and keel assembly

ABSTRACT

A fiber reinforced plastic boat hull with a tapered bottom recess receiving the upper end of a keel or center board and a floor or partition wall spanning the interior of the hull in spaced relation above the bottom thereof and secured around its periphery to the hull to form a reinforcing strut or stringer. The hull recess and upper end of the keel are of generally frusto-pyramid shape to center the keel in fixed wedged relation with the hull. Foam plastic fills the space between the bottom of the hull and the floor plate. The keel is a hollow molded plastic unit with a weight in the bottom thereof and also filled with foam plastic.

[ PLASTIC SAILBOAT BODY AND KEEL ASSEMBLY Helmut Stoeberl, 8201Eggstaett-Bachham, Germany Filed: Mar. 2, 1972 Appl. N0.: 231,331

Inventor:

[30] Foreign Application Priority Data Mar. 2, 1971 Germany P 21 09872.6

[5 6] References Cited UNITED STATES PATENTS 2,866,985 1/1959 Blackmore9/6 [111 3,747,550 1 July 24, 1973 3,080,845 3/1963 Pollak 114/1403,531,809 10/1970 Hegg 9/6 Primary Examinen-RichardA. SchacherAttorney-Benjamin H. Sherman. J. Arthur (.iross etal.

[57] ABSTRACT A fiber reinforced plastic boat hull with a tapered bottomrecess receiving the upper end of a keel or center board and a floor orpartition wall spanning the interior of the hull in spaced relationabove the bottom thereof and secured around its periphery to the hull toform a reinforcing strut or stringer. The hull recess and upper end ofthe keel are of generally frusto-pyramid shape to center the keel infixed wedged relation with the hull. Foam plastic fills the spacebetween the bottom of the hull and the floor plate. The keel is a hollowmolded plastic unit with a weight in the bottom thereof and also filledwith foam plastic.

27 Claims, 13 Drawing Figures PATENTED JUL 2 4 I975 SHEET 4PATENTEDJUL24I973 SHEET 7 BF 8 1 PLASTIC SAILBOAT BODY AND KEEL ASSEMBLYBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to fiberglass type boat hulls and particularly deals with areinforcing floor or partition wall arrangement to stiffen the hull andto a simplifled keel mounting arrangement.

2. Description of the Prior Art Fiber reinforced plastic or so-calledfiberglass boat hulls or bodies are known in the art, but heretoforethey had to be stiffened by a sandwich construction composed of shaped,stacked sheets or plates secured to the inside of the shell and coveredwith further layers of plastic. The stacked or sandwiched constructiongreatly increased the weight of the hull, provided spaces in which watercould enter, causing damage, especially in winter, due to ice formation,and would not accommodate deformation that might result from waterpressure, keel and mast loads and weight of the crew. Attempts tofurther reinforce such sandwich type plastic boat hulls with additionalframes, stringers and the like was not satisfactory because suchadditions materially add to the weight and production costs of thehulls.

SUMMARY OF THE INVENTION The present invention now provides fiberreinforced plastic, or fiberglass, boat hulls which are inexpensive tomanufacture and maintain, light in weight, high in strengthandresistance to deformation, provide a low center for the mast in thecase of sailboats, and have an improved keel mounting.

Sailboat hulls according to this invention provide easy removal of mast,keel, and rudder units so that they may be easily transported ontrailers or stored in minimum space. The removable keels for the hullsare quite thin with weighted bottom ends.

The floor or partition wall is preferably molded with an upturned flangearound its periphery that is bonded to provide a rigidifying stringerand the floor or partition is preferably bowed to provide a gutterimmediately adjacent the flange for draining water. Drain valvesextending through the hull can be provided at convenient locations fordraining the gutter. The flange is preferably stressed into conformitywith the hull to stress the partition or floor, creating a stretchedbeam effect for stiffening the assembly. It is also preferred to bow thefloor sheet or partition wall to provide a draining pitch toward thegutters and to present a substantially horizontal floor for the crewwhen the hull is tilted during sailing due to wind pressure on thesails.

The floor sheet or partition wall may span the entire length and widthof the interior of the hull or may terminate forwardly of the stern in avertical wall behind which is provided a trailing hull fin for mountingthe rudder.

Plastic foam material filling the space between the floor sheet andbottom of the hull and also filling the hollow keel body can be ofgraduated density to provide weight where desired.

Suspension bolts have nuts threaded on the upper ends thereof bottomedon the floor or partition wall suspend the keel from the hull and drawit tightly into its recess. The nuts are easily removed from the boltsto drop the keel from the hull.

It is then an object of this invention to provide a lightweight,inexpensive, strong, fiberglass boat hull having a stressed tray orfloor sheet reinforcing and stiffening the hull.

Another object of the invention. is to provide a fiber reinforcedplastic sailboat hull with a bottom recess receiving the upper end of adetachable keel.

A further object of the invention is to provide a fiberglass sailboathull with a frusto-pyramid shaped keel recess in the bottom thereofcentering a mating keel top which is tightened in the recess bysuspension bolts depending from the hull.

A further object of the invention is to provide a molded plasticsailboat hull with a bottom recess or well in the exterior thereofaccommodating a removable keel.

Other and further objects of the invention will become apparent to thoseskilled in this art from the following detailed description of theannexed sheets of drawings which, by way of preferred examples,illustrates several embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a somewhat schematictransverse crosssectional view through the boat hull and keelof a firstembodiment of this invention;

FIG. 2 is a view similar to FIG. I but showing a second embodiment ofthe invention;

FIG. 3 is a schematic longitudinal cross-sectional view through the boatbody and keel of the first embodiment;

FIG. 4 is an enlarged fragmentary transverse crosssectional viewillustrating details adjacent the water line of the boat hull;

FIG. 5 is a fragmentary cross-sectional view of a keel according tothisinvention;

FIG. 6 is a schematic view illustrating stresses on the boat hulloccurring during normal and heeling conditions;

FIG. 7 is a transverse cross-sectional view similar to FIG. I butillustrating a further embodiment;

FIG. 8 is a view similar to FIG. 1 but illustrating a still furtherembodiment;

FIG. 9 is a schematic transverse cross-sectional view of a front staymounting;

FIG. 9a is a longitudinalview of the mounting of F IG. 9;

FIG. 10 is a view similar to FIG. I with a further modification of thekeel or center board mounting;

FIG. 1 1 is a schematic transverse cross-sectional view of two differentfloorsheet or tray contours;

FIG. 12 is a schematic transverse cross-sectional view with differentembodiments of floor sheet or tray con tours and foam arrangements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, the hereinlistedl legends and reference numerals designate the following:

A. Transverse centering angle of the keel mounting B. Longitudinalcentering angle of the keel mounting C. Keel attachment bed WL. Waterline WL' Water line during heeling KB Ballast force, effective duringheeling GB Ballast weight, effecting during plane position PLat Lateralplan forces 1 Outer shell of boat body 2 Fin or keel 3 Foam filling inthe fin or keel 4 Foam filling in the boat body 5 Bottom floor tray 5'Bottom tray recess 5" Stringer flange of the bottom tray 5" Drainchannel of the bottom tray 5" Center support piece of the bottom tray 6Connection strip between bottom tray and boat body 7 Drain valve 8 Keelcentering member 9 Centering mounting in the boat body 9" Centeringmounting bottom piece 9" Longitudinal centering mounting surfaces 9"Centering mounting for removable keel 10 First reinforcing brace 11Second reinforcing brace 12 Keel attachment bolt 12 Attachment lugs 13Spacing tube 14 Nut 15 Eye 16 Ballast 16a Spacing projection 16b Centersurfaces of the ballast 16c Interspace 16d Plastic bales l7 Lateralplane surface of the keel 18 Load distribution plate 20 Transversebulkhead or partition 20 Flange of the transverse bulkhead 21 Opening inthe transverse bulkhead 22 Closing plate for transverse bulkhead 23Rudder blade 24 Rudder shank 24 Mounting bearing for rudder shank 25Mast base 26 Mast 27 Core 28 Filling channel 29 Supporting protrusionfor the ballast 30 Ballast foam 31 Deck 32 Front stay pivot 32" Frontstay anchor 33 Impact protector 50 Passage openings 51 Lower coveringlayer of the bottom shell 52 Foam inter-layer of the bottom shell 53Stringer flange of the bottom shell 54 Filling opening 55 Centersupporting piece In FIG. 1 a molded fiber reinforced plastic outer shellor hull 1 suspends a thin hollow keel 2 filled with plastic foam 3. Theinterior bottom of the hull 1 is filled with plastic foam 4. A plasticfloor sheet or tray 5 spans the interior of the hull 1 above the bottomthereof providing a recess therebeneath receiving the plastic foam 4.The floor 5 at the water line level WL has an upturned peripheral lip orflange 5" around the periphery thereof seated on the hull 1. A plasticstringer strip 6 overlies the lip or flange 5" and is bonded to both theflange 5" and the hull. In addition, the flange 5" is bonded to thehull. The foam 4 supports the floor 5 and reinforces the hull 1 toprovide stiffness and strength without added stringers and frames. Thefoam may be mixed with fibers or laminated with mats and the like foradded strength.

The upper end of the keel 2 has a frusto-pyramid shaped head 8 seated ina mating recess 9 molded in the hull. The head 8 is reinforced with afirst reinforcing brace 10.

A suspension bolt 12 extends through the deck sheet 5, top wall of therecess 9 and top wall of the head 8 and through a floor plate 14 and ahead plate 18. A nut 15 with a ring-head is threaded on the upper end ofthe bolt 12 to draw tightly so that the plates 14 and 18 will be seatedagainst their respective supports and the keel head will be drawntightly into the recess.

The keel 2 mounts a heavy weight 16 in the bowed lower end thereof. Theweight 16 is preferably spaced as shown at 16c from the walls of thebowed or humped bottom of the keel by means of plastic packs 16d.

As shown in FIG. 2, the deck sheet or floor plate 5 has depressions 5molded therein around the sides thereof providing gutters for waterdrainage and flap valves 7 extend through the hull to drain thesegutters.

In the enbodiment of FIG. 2, the deck sheet 5 has a raised hump 5".Strengthening ribs and tubes 10 and l l surround the hull recessdefining portion and extend into the hump 5 of the deck sheet.

As shown in FIG. 3, the deck sheet 5 terminates in an upstanding wall orbulkhead 20 forwardly from the stern of the hull and this upstandingwall has a flange 20' secured to the hull together with an opening 21 tothe space behind the wall. A wall 22 is also provided to close the spaceunder the deck adjacent the wall 20.

A rudder 23 is mounted on a rudder shaft 24 carried in a bearing tube24' provided in the hull behind the closure plate 22.

The back wall 20 extends to the level of the deck 31 and the compartmentbehind this wall receiving the rudder shaft can be hollow and sealed toprovide buoyancy. Since the space between the hull shell 1 and the deckfloor 5 is filled with foam sufflcient uplift will be maintained eventhough the ship is filled with water. Even though the hull and floor 5are damaged and punctured the foam filling will float the boat.

Because of the foam filling, as shown in FIG. 4, the hull 1 can have avery thin section 45 in the bottom thereof which is completelyreinforced by the foam filling 4. Further, if desired as shown in FIG.12, the foam can have incorporated therein so-called foam replacementbags 43 filled with air, and these bags may extend over a part or overthe entire range of the interspace between the bottom floor 5 and thehull l. Spacing members 44 can be provided to maintain the bags inposition during the filling of the spaces therearound with foam.

The recess 9 in the hull for receiving the head 8 of the keel isdesigned with side walls converging to a top wall 9", but it should beunderstood that the recess could be divided to receive divided heads onthe keel. The inclined side walls of the recess are at a transverseangle A with the longitudinal center plane of the boat which is selectedso that forces are favorably transmitted to the boat hull with a minimumof deformation. Angles between 30 and 60 are preferred.

The depth of the recess 9 is such that the wall 9 is adjacent the floor5 so that the two surfaces can contact and be connected as by means of aplastic layer.

As shown in FIG. 6, an underframe thus results with the recesses 9guiding the forces into the right or left sides of the boat hulldepending on the wind pressure direction, while in the verticaldirection the mounting 9 is supported by the bottom shell 5 andpush-and-pull loads are transferred as indicated by the arrows. Theforces which affect the keel 2 from the outside and which have to betransferred into the boat body consist essentially of forces PLat whichhave a lateral effect of a bending moment. The static forces GBresulting from the weight of the keel and the dynamic forces resultingfrom the keel mass during rough seas are directed downwardly and pullthe boat therewith. Thus the component parts are triangularly connectedon both sides of the centering mounting 9 and are mutually .sup-

' ported.

Since the recess 9 has only a small longitudinal expansion in the foreand aft direction as shown in FIG. 3, and since possible elastictransverse widening of the centering recess 9 is prevented under theinfluence of bending moments which occur due to the support of the boatbody which follows the center mounting longitudinally, the fore and aftlongitudinal centering mounting surfaces may have a different conicalangle B than the angle A as shown in FIG. 3. It should be alsounderstood that the center mounting recess 9 can be stepped whileconverging to provide a number of parallel connected support surfaces.

Since even a very small longitudinal displacement of the keel willdirect the boat toone side, care must be taken to maintain a fixedcenter line for the keel.

In fixedly mounting the keel to the hull, a hardenable attachment layerC of adhesive can be provided, or spacers can be used.

In the embodiment of FIG. 10, the removable keel 46 is illustrated asextending through a mounting 9"" opening upwardly in a wedge-like shapeand receiving the removable keel or center board 46. The bottom tray 5adjacent the keel 46 is provided with a recess 5 with edges turneddownwardly and fitting into the upper end of the recess 9"" so that awedge seat is provided when the two parts are assembled. This can besealed by means of plastic cement.

The removable keel 46 is guided approximately lincar at its upper andlower body mounting range 46' and is secured against dropping out of thehull by a head plate 47.

The floor tray 5 has a recess 48 dammed off by calking ledges 49 and thefloor is inclined toward the outside of the hull to flow water to thedrain channels 5". The recess 48 can be drained through suitable drainvalves.

The keel 2 is molded from two half-shells united together to provide asmooth surface form and the strengthening reinforcements 10 and 11 areinserted between the shell halves. They can be formed of glass fiber.

The load distributing plate 18 may be of laminated construction embeddedin the plastic in the strengthening layers.

The ballast weight 16 can have spacing humps 16a distributed on itssurfaces so that it can be centered in the half-shells of the keel. Inaddition, of course, the weight can be formed in two half-parts composedof lead or cast iron and positioned as desired during the foamingprocess. The half-sections have center surfaces 1612 as shown in FIG. 5,providing a space 16c therebetween maintained by spacer humps 16a.Plastic spacing bundles or bales 16d are inserted to provide a spacesurrounding the ballast weights. The entire assembly is then held inplace by the foam.

. is threaded in lugs 12 passed therethrough as shown. Since the keel Asalso shown in FIG. 5, the keel attachment bolt 12 anchored in theplastic foam. are additionally reinforced by fibers is hollow before itis filledwith the foam, electric conductors, tubes and the like can beinserted for attachment to pressure head indicators, current meters orthe like so that the speed of the boat can be measured.

As shown in FIG. 5, filling channels 28 can be provided in the keel forinjection of the foam plastic.

The filled-in foam 3 can be formulated as desired to provide differentdensities and can be heavier in the lower portion of the keel.Strengthening fibers such as glass, metal and the like can be mixed withthe foam to increase the keel strength.

The keels can be very thin in profile with the entire center of mass atthe bottom thereof and with as little weight as possible above thisbottom. I-Ieavy fillers such as metal powder and the like can be used toobtain sufficient weight concentration in the lower end of the keel.

The lugs 12' The floor 5 is easily inserted into the outer boat hull 1with a jig, preferably after the flanges 5" and 20 are coated withplastic to form the seal and create the stringer reinforcement describedabove. The shell is pressed against the foam replacement bodies 43 toobtain a desired loading and snug connection with the plastic. g I I Thestem of the boat is sufficiently rigid without requiring frames andstringers, and is capable of supporting the rudder shank 24 and rudderblade 23 in the bearing 24' extending high above the water line WL,preferably up to the deck 31, thereby avoiding the necessity of a sealpacking. The bearing 24' is formed during the production of the hull land is sufficiently attached thereto and reinforced by strengtheninginserts. In the FIG. 2 embodiment, and as also illustrated on the leftside of FIG. 12, the bottom floor 5 is inclined toward the outsidestarting from the center line to better discharge spray water and toprovide a bottom on the wind-side, which is less inclined to providebetter standing safety for the crew. The drain channel 5" cmbodied inthe bottom shell 5 is deeper than the level of the bottom shell or floorfor better drainage without flowing back during a change of listing ofthe boat. The

drain valve 7 is arranged at suitable places on one or both sides of theboat which is lowest during the listing or heeling of the boat. At rest,the drain flaps 7 remain open, and rain and spray water are run off.Therefore, it is not necessary to cover boats of this design with atarpaulin since they are always fully drained. The center recess 48 inthe embodiment on the right side of FIG. 11 can be drained by a sterndrain flap.

As is also shown in FIG. 2, the bottom shell is designed with a centersupport piece 5"" extending over the entire length of the shell anddesigned in a trapezoid shape. The center support piece 5"" stiffens thebottom shell or floor 5 and also the boat body. The center support piece5"" also serves as the keel load carrier and eliminates the necessityfor a keel beam extending over the length of the boat which increasesthe weight of the boat.

As shown in FIGS. 3 and 7, the mast base or pedestal 25 is reinforced bya brace 25' laminated on the inner side of the center support 5"" of thefloor tray or shell 5. The front mast stay 32 is preferably pivoted toits base 32' which is also laminated on the center support 5 of thefloor tray 5.

As shown in FIGS. 9 and 9a, the floor 5 with its center support section5"" is formed with a bulge or pyramid-like hump at the front stay pivot32, which is designed triangularly and is secured to a strengtheninglaminate layer 32". Bending stresses are reduced and redirected intopush-and-pull forces in the laminate. Strengthening layers are providedfor impact protec- -tion at 33, as shown in FIG. 9a. The impactprotection 33 can be molded into the boat hull 1 on both sides and takethe form of a metal layer or additional laminate layer.

The center support piece 5 can have longitudinal profiling open towardthe top or toward the bottom with a U- or l-I-shape, thereby providing agood reinforcement for attaching the keel as illustrated in FIG. 7,since cross-bars 34 of the support piece will rest directly against thecorresponding walls of the center mounting 9 of the hull l and can beconnected during assembly by means of plastic adhesive. In the samemanner the mast 26 and the front stay 32, mounting belts for the crew,and similar things may be attached in a simple manner to the upwardlyextending crossbars 35 without having to bore holes in the shell 5.

The center support piece 5"" can take the form of a closed longitudinaltube as shown in FIGS. 8 and 12, and can be made of metal or plastic.The tube can have passage openings 50 at its outside, as shown in FIG.8, and can have a filling opening 54 as shown in FIG. 12 for foam. Thetube thus serves as a foam distributor to insure filling of the spacebetween the hull and the floor tray, especially when the floor rises tothe levels as shown in FIGS. 11 and 12. The tube feed for the foamprevents air bubble formation, and after the space is filled with foam,the opening 54 can be closed.

As shown in FIG. 2, one or several centering mounting strengtheningmembers 10 and 11 may be laminated in the area of the connection of thecentering mounting 9 with the keel 2, and in the boat body shell 1, andthese may extend to the center support piece 5" and connected therewithby flanges, adhesive layers and the like so that a mounting of increasedstrength is obtained. Spacing tubes 13 may be mounted around theattachment bolts 12 to support axial stresses.

FIGS. 8, 10 and 11 show additional contours for the floor tray 5 withFIG. 8 showing protrusions 36 supporting the track 37 for the mainsheet. Additional longitudinal stringers 38 are provided and can beshaped to provide storage compartments 40 under the deck 31. Drainpassages 41 in the humps or protrusions 36 drain toward the channel 5"and toward the drain valve 7 as shown in the left side of FIG. 8. Thecircumferential stringer flange 5 may be extended and attached to thelongitudinal wall 38 as shown at FIG. 8 on the right side to form afurther longitudinal strengthening arrangement. Ad edge connector 42 isprovided to unite the deck 31 to the hull.

As shown in FIG. 4, the floor tray 5 can have two layers including thetop floor layer 5 and a bottom layer 51 with a foam filler 52therebetween. The filler may be hard foam or may be a soft fleece layer.The layers 5 and 51 are pulled together around their peripheries asillustrated at 5" and may be bowed to form the drain channel 5". Astringer strip 6 may cover the upper ends of the joined together shells5 and 51, and a drain valve 7 can be provided for the channel 5.

From the above descriptions, it therefore will be understood that thisinvention provides an integrated, lightweight molded plastic boat bodystiffened by plastic foam and free from heretofore necessary ribs. Thebody consists only of two essential components and affords a novel keelmounting.

I claim as my invention:

1. A plastic boat body comprising a molded hull portion with a keelreceiving recess in the bottom thereof, a molded plastic floor tray insaid hull and sealed around the periphery thereof to the hull, a moldedplastic keel having a head portion fitting said recess in the bottom ofthe hull and suspension means attaching the keel to the hull.

2. The boat body of claim 1 wherein the hull recess has afrustro-pyramid shape.

3. The boat body of claim 1 wherein the space between the hull and thefloor is filled with plastic foam.

4. The boat body of claim 1 wherein the floor tray is flanged upwardlyin the hull and has the flange thereof bonded to the hull for forming areinforcing stringer.

5. The boat body of claim 4 wherein the stringer is covered with areinforcing plastic strip.

6. The boat body of claim 1 wherein the molded plastic hull has a deckand the periphery of the floor tray extends upwardly toward the deck andthe space between the hull and floor tray is filled with plastic foamextending upwardly toward the deck level.

7. The boat body of claim 1 wherein the space between the hull and floortray has bags therein adapted to be fllled with air, foam or otherlightweight material.

8. The boat body of claim 1 wherein the floor tray is inclined from alongitudinal center line to the boat hull.

9. The boat body of claim 1 including two floor trays with a foam layertherebetween.

10. The boat body of claim 1 wherein the floor tray is at the waterlevel of the hull.

11. The boat body of claim 1 wherein the floor tray has a peripheraldrain channel and a drain valve is provided in the hull to drain waterfrom the channel.

12. The boat body of claim 1 including reinforcing braces between thefloor and hull for supporting a mast.

13. The boat body of claim 1 including reinforcing members between thefloor tray and surrounding the recess defining portion of the hull.

14. The boat body of claim 1 wherein the floor tray has a longitudinallyextending supporting piece thereunder.

15. The boat body of claim 1 wherein additional strengthening laminatelayers are provided under the floor tray for a mast pedestal and a frontstay.

16. The boat body according to claim 1 including a distributor tube inthe floor tray for filling the space between the tray and hull withplastic foam.

17. The boat body of claim 1 including a separate layer of materialbetween the head of the keel and the recess.

18. The boat body of claim 1 including a spacer tube surrounding thesuspension mounting for the keel between the hull and floor tray.

19. The boat body of claim 1 wherein the keel is hollow, has a ballastweight at the bottom thereof and is filled with plastic foam.

20. The boat body of claim 1 wherein the keel is formed from two moldedplastic halves.

21. The boat body of claim 1 wherein the keel is hollow and filled withmaterial having a low specific weight in the upper end thereof and ahigh specific weight in the lower end thereof.

22. The boat body of claim 1 wherein the keel is hollow and containsconduits and the like for recorders and measuring devices.

23. The boat body of claim 1 where the stern of the hull has a molded-intubular bearing for the rudder shank.

24. The boat body of claim 1 wherein the deck tray terminates short ofthe stern of the hull in an upstanding bulkhead.

25. The boat body of claim 1 wherein the recess of the hull is slottedfor receiving a removable center board.

26. A fiber reinforced plastic sailboat construction comprising aone-piece molded plastic hull with an elongated tapered recess in thebottom thereof along the longitudinal center line, a molded plastic keelhaving a head fitting said recess and suspension bolts securing the headin said recess.

27. A fiber reinforced plastic sailboat construction comprising aone-piece molded plastic hull with an elongated tapered recess in thebottom thereof along the longitudinal center line, said recess having aflat top wall, a molded plastic keel having a head fitting said recess,suspension bolts securing the head in said recess, and a molded plasticfloor secured around its periphery in the hull resting on said top wallof the recess.

1. A plastic boat body comprising a molded hull portion with a keelreceiving recess in the bottom thereof, a molded plastic floor tray insaid hull and sealed around the periphery thereof to the hull, a moldedplastic keel having a head portion fitting said recess in the bottom ofthe hull and suspension means attaching the keel to the hull.
 2. Theboat body of claim 1 wherein the hull recess has a frustro-pyramidshape.
 3. The boat body of claim 1 wherein the space between the hulland the floor is filled with plastic foam.
 4. The boat body of claim 1wherein the floor tray is flanged upwardly in the hull and has theflange thereof bonded to the hull for forming a reinforcing stringer. 5.The boat body of claim 4 wherein the stringer is covered with areinforcing plastic strip.
 6. The boat body of claim 1 wherein themolded plastic hull has a deck and the periphery of the floor trayextends upwardly toward the deck and the space between the hull andfloor tray is filled with plastic foam extending upwardly toward thedeck level.
 7. The boat body of claim 1 wherein the space between thehull and floor tray has bags therein adapted to be filled with air, foamor other lightweight material.
 8. The boat body of claim 1 wherein thefloor tray is inclined from a longitudinal center line to the boat hull.9. The boat body of claim 1 including two floor trays with a foam layertherebetween.
 10. The boat body of claim 1 wherein the floor tray is atthe water level of the hull.
 11. The boat body of claim 1 wherein thefloor tray has a peripheral drain channel and a drain valve is providedin the hull to drain water from the channel.
 12. The boat body of claim1 including reinforcing braces between the floor and hull for supportinga mast.
 13. The boat body of claim 1 including reinforcing membersbetween the floor tray and surrounding the recess defining portion ofthe hull.
 14. The boat body of claim 1 wherein the floor tray has alongitudinally extending supporting piece thereunder.
 15. The boat bodyof claim 1 wherein additional strengthening laminate layers are providedunder the floor tray for a mast pedestal and a front stay.
 16. The boatbody according to claim 1 including a distributor tube in the floor trayfor filling the space between the tray and hull with plastic foam. 17.The boat body of claim 1 including a separate layer of material betweenthe head of the keel and the recess.
 18. The boat body of claim 1including a spacer tube surrounding the suspension mounting for the keelbetween the hull and floor tray.
 19. The boat body of claim 1 whereinthe keel is hollow, has a ballast weight at the bottom thereof and isfilled with plastic foam.
 20. The boat body of claim 1 wherein the keelis formed from two molded plastic halves.
 21. The boat body of claim 1wherein the keel is hollow and filled with material having a lowspecific weight in the upper end thereof and a high specific weight inthe lower end thereof.
 22. The boat body of claim 1 wherein the keel ishollow and contains conduits and the like for recorders and measuringdevices.
 23. The boat body of claim 1 where the stern of the hull has amolded-in tubular bearing for the rudder shank.
 24. The boat body ofclaim 1 wherein the deck tray terminates short of the stern of the hullin an upstanding bulkhead.
 25. The boat body of claim 1 wherein therecess of the hull is slotted for receiving a removable center board.26. A fiber reinforced plastic sailboat construction comprising aone-piece molded plastic hull with an elongated tapered recess in thebottom thereof along the longitudinal center line, a molded plastic keelhaving a head fitting said recess and suspension bolts securing the headin said recess.
 27. A fiber reinforced plastic sailboat constructioncomprising a one-piece molded plastic hull with an elongated taperedrecess in the bottom thereof along the longitudinal center line, saidrecess having a flat top wall, a molded plastic keel having a headfitting said recess, suspension bolts securing the head in said recess,and a molded plastic floor secured around its periphery in the hullresting on said top wall of the recess.